Ca-ATPase activity in salivary glands of rats treated with reserpine, isoproterenol, terbutaline or dobutamine.

ABSTRACT

Ca-ATPase activity (mol Pi/mg protein per min) of submandibular and parotid glands after injection of single or multiple (over seven days) 0.5 mg/kg doses of reserpine was the same as in untreated glands. Twice daily doses (50 mg/kg body wt) of the non-selective beta-adrenergic agonist, isoproterenol, for six days, increased Ca-ATPase specific activity of parotid gland by 17 per cent but that of submandibular gland was the same as controls; with dobutamine, the same dosage caused a 53 per cent decrease in submandibular activity and a 31 per cent decrease in parotid. The activity of the entire parotid gland was markedly increased by all three beta-agonists, and this was generally a reflection of the induced increase in gland size. The submandibular gland had an increase in total Ca-ATPase activity only with isoproterenol. As gland weight did not change after reserpine, total glandular Ca-ATPase activity was also not altered by it. Thus, calcium accumulation and reduction in Ca-ATPase activity are not necessarily related. However, the dobutamine-induced decrease in Ca-ATPase activity of both glands suggests that there is a beta 1-mediated regulation of this enzyme.